Proposal: Language feature "return if myCondition"

[dibley1973]

I am a fan of one line guard clauses like.

Ensure.IsNotNull(myArgument, nameof(myArgument))

Which would throw an exception if the argument value is null.

So in the same vein, my currently most desired new C# feature would be a "return if" kind of statement.

var myCondition = DoSomeChecks(...);
return if myCondition;

Which would return from a method if the condition is true. It would simply be syntatic-sugar for

var myCondition = DoSomeChecks(...);
if (myCondition)
{
    return;
}

Is this a language feature which could be considered for inclusion in a future version of C#?

[alrz]

What would be the advantage of this?

return if (myCondition);
if (myCondition) return;

təˈmeɪtoʊ;
təˈmɑːtəʊ;

[ufcpp]

gaurd statement? #138

[dibley1973]

@alrz - because some companies (like where I work) enforce curly braces for statements for the condition, even if its a one liner. If added to the language as per my post then people working for companies which require these code rules can have more succinct code.

Having to have the braces means your guard clauses can take up half your screen!

[dibley1973]

@ufcpp - nice to see others have already proposed it.

[alrz]

because some companies (like where I work) enforce curly braces for statements for the condition,

Riot.

Seriously though, you want this feature to get around your company's coding convention? that really doesn't seem to be a good reason to add a language feature IMO. I'd expect that such strict guidelines to forbid using return if constructs to avoid inconsistencies. So you'd be back to where you started. I'm pretty sure your company requires blocks for a reason, no?

[jnm2]

See #325, #453, and #724 for existing discussion.

[yaakov-h]

Well then,

return if (myCondition);
if (myCondition) { return; }

As much as I like the idea of a guard statement, is an entirely new language feature really worth reordering a construct to save a handful of characters?

[magol]

But if the function must return a value, how do you do that with this proposed solution?

[asyncawaitmvvm]

guard, defer, return if... these all go into file 13. My friend in high school joked that we should have an "unless" statement. Throw that in there too.

[yaakov-h]

That's #560. 😄

[Mteheran]

Take a Look to the following code:

public decimal? CalculateNewPlannedAmountForLastPaidLine(EscalationDataAmount escalationDataAmount, decimal? rootLineTotalPlanned, DateTime? plannedDate)
        {
            if (!rootLineTotalPlanned.HasValue)
            {
                return null;
            }

            decimal newPlanned = CalculateNewPlannedAmount(escalationDataAmount, plannedDate);

            return newPlanned - rootLineTotalPlanned.Value;
        }

Right now we cannot mix the first condition (if (!rootLineTotalPlanned.HasValue))
on the last return. I think this could be useful in this case.

[CyrusNajmabadi]

You can already write this as:

public decimal? CalculateNewPlannedAmountForLastPaidLine(EscalationDataAmount escalationDataAmount, decimal? rootLineTotalPlanned, DateTime? plannedDate)
    => rootLineTotalPlanned.HasValue
        ? CalculateNewPlannedAmount(escalationDataAmount, plannedDate) - rootLineTotalPlanned.Value
        : default(decimal?);

I think there are already enough language features to help get brevity here. I don't think a new form of 'return' is really needed.

[asyncawaitmvvm]

That's #560. 😄

I don't know who you are or how you found that but you made my day.